Drobo

Capacity gauge LEDs turning on in stages after 5C boot process complete

The capacity gauge LEDs lights do not show immediately all used capacity after boot is complete.
Instead, since adding a new drive, they turn on in “stages”, even after the Drobo has mounted on the desktop.
First 3 lights come on, the another 2 and then the last 6th one.
It works otherwise ok and reports the right used capacity (as also per Dashboard information).
I thought this to be a “first time” thing that would not happen in the future, but after many days of usage, still the same behaviour after boot.
Is this normal? why is the capacity not reported all at once by the LEDs and it takes a while to “build up”?

History:

  1. I started with the following drive configuration: 2TB+2TB+2TB+500GB(SSD)+320GB
  2. after using the spin down function for about a week, the 320GB drive (really old one) was not detected as connected at boot (although SMART logs say it is fine, I think the Drobo decided it was not alive anymore as it would spin too slowly up to speed at boot); the Drobo did his work and resilvered the data on the remaining 4 drives in about 2-3 hrs (green/yellow flashing LEDs on the 4 remaining drives).
  3. I disabled the spin down function, and added a 5th 2TB drive.
  4. now at the end of the boot process, first 3 blue LED lights come on, the drive mounts, and then the rest of the LEDs light up after a short while.